Machine for forcibly casting dental bridges.



N0. 708,8". Patented Sept. 9, I902.

M. w. HULLINGSWURTH.

MACHINE FOR FQRGIBLY CASTING DENTAL BRIDGES.

(Application filed May 19, 1902.) I (No Model.) 3 sheets sheet l.

WITNESSES: 7 "1mm 4 TTORIIEYS No. 708,8. Patented Sept. 9, I902.

M. W. HOLLINGSWURTH.

IV IACHINE FOR FORCIBLY CASTINGDENTAL BRIDGES.

(Application filed May 19, 1902.)

' (No Model.) H 3 smu -5m; 2.

5y. 4 X Z f; :2 I A WITNESSES: I v I "IVE/(TOR ./IW' 77W! By M Arron/ 5m.

No. 708,8". v Patented Sept. 9, 4902.

l M. w. HOLLINGSWOBTH.

MACHINE Fun FOBQIBLY CASTING DENTAL amass.

. (Application filed May 19, 1902.)

( No Mo del.) Y 3 Sheets-8heet 3.

IIIIIlIIlIIIIIIIIIA7IIIII//\ :j "V

will! 'INVENTUR fiLQ/IW 7 mm.

I 2 .4 TTORIIEKS WI TNESSES UNITED STATES PATENT OFFICE.

MERRILL WV. HOLLINGSWORTH, OF PHILADELPHIA, PENNSYLVANIA.

MACHINE FOR FORCIBLY CASTING DENTAL BRIDGES.

SPECIFICATION forming part of Letters Patent No. 708,811, dated September 9, 1902.

Application filed May 19, 1902.

To all whom it may concern.-

Be it known that I, MERRILL W. HOLLINGS- WORTH, a citizen of the United States, residing at Germantown, Philadelphia, county of Philadelphia, and State of Pennsylvania, have invented a new and useful Improvement in Machines for Forcibly Casting Dental Bridges, of which the following is a full, clear, and exact description, reference being bad to the accompanying drawings, which form a part of this specification.

My invention relates to the manufacture of dental bridges.

The object of the invention is to forcibly cast the bridge integrally with the pillar cap or caps, to which it is to be united with suffi cient rapidity to prevent chilling of the molten gold, andto cast it without utilizing a quantity of gold much in excess of that entering into the casting itself.

In the drawings, Figure I is a plan of the machine; Fig. 2, a side elevation; Fig. 3, an end view; Fig. 4, a side view, partially in section, of the table and the pillar-caps and wax pattern of bridge supported on the metal-plunger. Fig. 5 is a side elevation of the table after the mold is formed. Fig. 6 is a transverse section through the plunger, Fig. 5. Fig. 7 is a side View, partially in section, of the machine ready for casting. Fig. 8 is a similar view showing the position of the parts at the end of the casting operation.

The pillar-caps X Y, which are designed to engage the teeth between which the bridge is to be supported, are prepared, preferably of gold, in any well-known way. The wax pattern Z of the bridge is then formed on an articulator and united at the end to the pillar-caps. The pillar-caps and Wax pattern are then mounted on the metal-plunger A, which is dropped intoan orifice formed in the table B, and a ing b, depending therefrom, as shown in Fig. 4. The table B is provided with a handle B, and legs 17. A mold O, of marble-dust and plaster or other suitable investment material, is then formed around the pillar-caps, wax pattern, and that part of the metal-plunger A projecting above the table. A surface-coating C of the material of which the mold is composed is also preferably spread over the floor of the table, and a slight depression c is formed in this surface-coating to Serial No. 107,901. (No model.)

contain the gold or other metal to be melted and to provide a channel for the passage of the melted gold to the mold. A small orifice c is left in the mold at the mouth of said channel. (See Figs. 1, 5, and 7.) It is also advisable to insert a wire 10 through the mold to the casting-chamber, which wire is withdrawn prior to the casting operation, thereby forming a vent w for any air or excess of metal that may be injected into the castingchamber in the casting operation. It should be understood, however, that the depression 0 for containing the metal and guiding it to the mold need not be formed of the investment material, but may be permanently formed in the table. In short, any arrangement may be adopted whereby the meltingpan is adjacent to the mouth of the passage. The metal-plunger A has formed in its lower end a screw-orifice adapted to receive the screw-threaded shank of a handle D, (see Fig. 5,) by means of which the metal-plunger A is withdrawn from the mold. By any suitable application of heat, such as a Bunsen burner, the Wax is melted out of the mold,

the pillar-caps being left in the mold. A carbon-plunger A is then inserted into the passage a, from which the metal-plunger A has been withdrawn, and thetable is pivoted to the supporting-frame E by means of screws e in said frame engaging holes 1 in the side edges of the table. The handle B of the table rests upon the raised rear end of the frame E, and the table itself also rests directly on the frame. I provide the following means for tilting the table on its pivot:

G is a lever pivoted between its ends to the supporting-frame. One end of this lever rests upon the pin 9 and engages the rear corner of the table, while the other end is connected, by means of the link H, with one end of the lever I, the other end of which is pivoted to the frame.

The carbon-plunger A rests upon the front end of a cam K, formed on the frame. The plunger is of such length that its upper end lies substantially flush with the depression 0.

The operation of the machine is as follows: The gold or other metal to be cast is placed in the melting-pan or depression 0. The operator grasps the lever I with the fingers of one hand, placing his thumb back of the frame. With the other hand he holds the blowpipe and fuses the metal. (See Fig. 7.) When the metal is in proper condition for casting, the lever G is gently pulled back, thereby tilting the table and causing the metal to flow through opening 0 and over and upon the upper end of the carbonplunger. In the meantime the lower end of the carbon-plunger has passed over the front portion of cam K. This portion of the cam is so shaped as to maintain the carbon pencil in a substantially fixed position with relation to the casting-table during the preliminary tilting operation just described. The rear portion of the cam, however, is so shaped that in the further tilting movement of the table the carbon-plunger will be projected up into the passage a, leading to the gate of the mold. As soon as the metal has flowed over the upper end of the carbon-plunger the lever G is quickly pulled farther back, tilting the table into the position shown in Fig. 8 and causing the carbon pencil to be swiftly projected into the passage a, carrying with it the molten metal and forcibly injecting it into the casting-chamber. The gold is cast onto the pillar-caps and unites therewith.

The method of operating the apparatus just described requires some delicacy of manipulation, as there is some danger of a premature upsetting of the table. If, also, the bridge to be formed is of large size, requiring a large injection of metal, the preliminary tilting of the table may not enable a sufficient quantity of the metal to be injected into the orifice at above the carbon-plunger, as the opening 0, through which the metal passes, is necessarily somewhat small. It may therefore be found more convenient and sometimes almost necessary to initially tilt the table, not by manipulating the lever G, but by tilting the frame itself on its front end as an axis. The table may thereby be preliminarily tilted, if desired, to a substantially vertical position without projecting the carbon pencil upwardly, permitting the maximum quantity of metal to flow through the opening 0. The lever G is then moved quickly through its extreme movement, causing the carbon pencil to be projected into the orifice a, as before described. It is obvious, therefore, that it is not essential to make special provision for the tilting of the table, as this may be accomplished by inclining the entire machine; nor do I limit myself to the details of construction described, as these may be Varied without departing from my invention.

When the metal is melted in a separate crucible, then poured into the mold, and then forcibly injected into the casting-chamber, partial chilling cannot be avoided, owing to the very small quantity of metal which is utilized. With my apparatus, however, I have the capacity of injecting the metal into the casting-chamber immediately after fusion is effected, thus reducing to a minimum the time in which the metal had an opportunity to chill. I avoid also the necessity for using a quantity of metal much in excess of that actually required to form the bridge itself.

Having now fully described my invention, what I claim, and desire to protect by Letters Patent, is

1. In a machine for casting dental bridges, the combination, with a normally substantially horizontal melting-pan, of a mold having a casting-chamber and a normally upwardly-extending passage beneath and communicating with said casting-chamber, a plunger beneath and adapted to said passage, there being an opening into said passage adjacent to said plunger and communicating with said meltingpan, whereby by the tilting of said pan the melted metal is passed into said passage, and means to force said plunger into said passage, thereby injecting the melted metal into the casting-chamber.

2. In a machine for casting dental bridges, the combination, with a normally horizontal melting-pan, of a mold having a castingchamber, and a passage communicating with said casting-chamber, a plunger adapted to said passage, there being an opening into said passage adjacent to and communicating with said melting-pan, whereby by the tilting of said pan the melted metal is passed into said opening, and means to force said plunger into said passage, thereby injecting the melted metal into the casting-chamber.

3. In a machine for casting dental bridges, the combination with the mold having a casting-chamber and a passage leading thereto, of a normally horizontal melting-pan, an opening into said passage adjacent to and communicating with said melting pan, a plunger adapted to said passage, and means to successively tilt said pan toward said opening and force said plunger into said passage, therebysuccessively passing the melted metal into said passage and forcibly injecting it into the casting-chamber.

4c. In a machine for casting dental bridges, the combination, with the mold having a casting-chamber and a passage leading thereto, of a normally horizontal melting-pan, an opening into said passage adjacent to said passage, and means for successively tilting said pan and then simultaneously further tilting said pan and forcing said plunger into said passage.

5. In a machine for casting dental bridges, the combination, with the mold havingacasting-chamber and a passage leading thereto, of a table sustaining said mold and having an orifice therein coinciding with said passage, a plunger in said orifice adapted to said passage, means for simultaneously tilting said table and forcing said plunger into said passage.

6. In a machine for casting dental bridges, the combination, with the melting-table having an orifice, a plunger adapted to said orilice, a frame on which said table is pivoted,

and means for tilting the table relatively to said frame, and simultaneously forcing said plunger upwardly.

7. In a machine for casting dental bridges, the combination, with the mold having a casting-chamber, a passage leading thereto and an opening into said passage, of a supportingframe, a table having pivoted thereto a melting-pan on said table adjacent to said opening, said table having an orifice coinciding with said passage, a plunger in said orifice and extending beneath the same and adapted to said passage, a cam on said frame beneath said plunger and means for tilting said table relatively to said frame, thereby moving said plunger along said cam, whereby said cam forces said plunger into said passage.

8. In a machine for casting dental bridges, the combination, with the mold having a casting-chamber, a passage leading thereto and an opening into said passage, of a supportingframe, a table pivoted thereto, a melting-pan on said table adjacent to said opening, said table having an orifice coinciding with said passage, a plunger in said orifice and extending beneath the same and adapted to said passage, a cam on said frame beneath said plunger, a lever pivoted to said frame and engaging said table, a second lever pivoted to said frame, and a link engaging said lever, wherebysaid table is tilted relatively to said frame, thereby moving said plunger along said cam and causing said plunger to be forced'into said passage.

9. In a machine for casting dental bridges, the combination, With the casting-table having an orifice, a plunger adapted to project upwardly through and above said orifice and to sustain the pattern, and a separate rod adapted to engage the lower end of said plunger, whereby the plunger may be withdrawn after the formation of the mold.

In testimony of which invention I have hereunto set my hand, at Philadelphia, on this 16th day of May, 1902.

MERRILL W. HOLLlNGSWOR-Tll.

\Vitnesses:

M. F. ELLIS, M. M. HAMILTON. 

